Changing the order of triple summation

  • Thread starter Thread starter hjcho
  • Start date Start date
  • Tags Tags
    Summation
Click For Summary
SUMMARY

The discussion focuses on changing the order of triple summation in the expression $$\sum^N_{k=0} f(k) \sum^k_{n=0}\sum^{N-k}_{m=0} g(k,n)h(k,m)A(n+m)$$ to a form where the variable x, defined as x = n + m, ranges from 0 to N. The participants clarify the constraints on the variables k, n, and m, emphasizing that k can take any value up to N, while n must be less than k, and m can vary such that m + k does not exceed N. The goal is to rewrite the summation to facilitate the new variable x.

PREREQUISITES
  • Understanding of triple summation notation and its properties
  • Familiarity with the concepts of variable substitution in summations
  • Knowledge of functions and their manipulation in mathematical expressions
  • Basic grasp of combinatorial mathematics and constraints on indices
NEXT STEPS
  • Research techniques for changing the order of summation in multiple sums
  • Study variable substitution methods in mathematical expressions
  • Explore combinatorial identities that may simplify summation expressions
  • Learn about the implications of variable constraints in summation limits
USEFUL FOR

Students and educators in mathematics, particularly those focusing on combinatorics, calculus, and advanced algebra, as well as anyone involved in mathematical problem-solving and expression manipulation.

hjcho
Messages
1
Reaction score
0

Homework Statement


I want to change the order of triple summation. it follows:
$$\sum^N_{k=0} f(k) \sum^k_{n=0}\sum^{N-k}_{m=0} g(k,n)h(k,m)A(n+m)$$

=>
I need to set the variable x(=n+m) go from 0 to N firstly, and then further go on...
$$\sum^N_{x=0} A(x) \cdots \cdots$$

But, I don't know how... please answer this question.
Thank you very much

Homework Equations





The Attempt at a Solution





 
Physics news on Phys.org
welcome to pf!

hi hjcho! welcome to pf! :smile:
hjcho said:
$$\sum^N_{k=0} f(k) \sum^k_{n=0}\sum^{N-k}_{m=0} g(k,n)h(k,m)A(n+m)$$

let's write it in ordinary english …

k can be anything (up to N), but n must be less than k, and m+k can be anything (up to N)

ok, so how would we write it if we started with m? :wink:

(hmm … are you sure that last N, above the ∑, shouldn't be an n ? :redface:)
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 18 ·
Replies
18
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
3
Views
2K
Replies
17
Views
2K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 21 ·
Replies
21
Views
3K